Computational Aerodynamic Investigations on Wash Out Twist Morphing MAV Wings

Fixed-wing MAV with morphing wing configuration is seen as the future design requirements for more aerodynamic efficiency. Wash in twist morphing MAV wings have shown a promising ability by producing smoother lift behavior and exhibited a significant increase in lift performances. However, the wash in twist morphing wings also suffer from massive drag penalties as compared to rigid or membrane (baseline) wings. Thus, the objective of this paper is to explore the aerodynamic performances of another morphing configuration known as wash out twist morphing MAV wing with a view towards the improvement of the drag performances of morphing MAV wing. Technically, the wash out twist morphing (TM) wing has deformation characteristics which are opposite from those of the wash in morphing wing. The force execution of the wash out morphing wing is similar to the wash in wing but with reversed vector direction. The investigation was carried out based on Fluid-Structure-Interaction (FSI) simulation method. The simulation was conducted in a 3D, quasi-static linear structural model combined with a steady-state, incompressible, and turbulent flow model. Three levels of the wash out morphing force (5N, 3N, and 1N) were used here to evaluate the morphing performances together with the baseline wing models (membrane wing and rigid wing). The lift coefficient results show that the wash out TM wings produced inferior lift performances compared to the baseline wings. This is due to weak vortices interactions, which lead to substantial adverse pressure on the TM wings. Meanwhile, TM wings have slight advantages in producing better drag performances than the rigid and membrane wings. Vortices study discovered that the TM wings have a weak tip vortex formation, which subsequently induces lower drag magnitude. However, the drag advantages found on the TM wings are still unable to overcome the lift drawbacks, which in turn, reducing the overall aerodynamics efficiency performances.